doc: qemu-riscv: describe CONFIG_DEBUG_SBI_CONSOLE

In main U-Boot the SBI DBCN extension can be used to supply a debug
console.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

diff --git a/doc/board/emulation/qemu-riscv.rst b/doc/board/emulation/qemu-riscv.rst
index 8a5eb1eda567a26a87853cfaae67c59ef4b106e1..8388e13d96d67a11fb0ebb92868d7efcace3c335 100644 (file)
--- a/doc/board/emulation/qemu-riscv.rst
+++ b/doc/board/emulation/qemu-riscv.rst
@@ -171,3 +171,8 @@ The following settings provide a debug UART for the virt machine::
     CONFIG_DEBUG_UART_NS16550=y
     CONFIG_DEBUG_UART_BASE=0x10000000
     CONFIG_DEBUG_UART_CLOCK=3686400
+
+To provide a debug UART in main U-Boot the SBI DBCN extension can be used
+instead::
+
+    CONFIG_DEBUG_SBI_CONSOLE=y